how can I make the world generation always use one specific world?

I'm creating a SkyFactory-style modpack and adding my own mod to it. I have a question — how can I make the world generation always use one specific world?
I already have the world folder I want to use. For example, when someone creates a new world, I want it to automatically load my predefined world instead of generating a new one.

I'm still new to MCreator, so please explain it in a simple way.